How to Manage and Control Kochia in Corn and Soybeans

Kochia close-up

Kochia is a shallow germinating plant, allowing it to be a particularly competitive weed in dry and/or saline soils.

Kochia (Kochia scoparia), also called Mexican fireweed, burning bush and summer cypress, is primarily found across the Great Plains states in fields where the soil has been disturbed, along fencelines, ditches and poorly tended landscapes. It is particularly well-adapted to cultivated, dryland agriculture.

Identifying Kochia

Kochia is a bushy summer annual with many branches forming pyramid or cone-shaped bushes that may grow 7 feet in height or taller. Stems are erect, spreading and greatly branched from the base, and are usually soft and hairy, though occasionally smooth. Their typical yellowish-green to green color often turns red as the plant matures, yet both colors can appear on a plant at the same time.

The leaves of the kochia plant are 1/2 to 2 inches long, alternate and lance-shaped, with fringed hairs on the margins. The leaf’s upper surface is typically smooth, while soft hairs usually cover the lower surface. Seeds are oval, dull brown in color and slightly ribbed.

Kochia exhibits rapid growth. Flowers are inconspicuous, greenish and form short, dense, terminal, bracted spikes. Each plant produces thousands of flowers, which generally develop from July to September.

Kochia Biology and Management from University of Illinois has additional details on identifying kochia.

Rapidly growing Kochia weed, often called tumbleweed
The rapidly growing kochia weed, often called tumbleweed, contains many branches that form pyramid or cone-shaped bushes. The plant may grow 7 feet in height or taller. Stems are erect, spreading and greatly branched from the base, and are usually soft and hairy.

Potential Damage and Economic Impact

Kochia roots can grow as deep as 16 feet under drought conditions. With severe infestations and poor crop competition, kochia can create up to 100 percent crop loss.

Kochia stays green well into fall and steals valuable moisture from cropland. This can lead to considerable yield losses, either from delayed grain harvest due to weed moisture content in the field, or from increased grain moisture levels due to weed debris mixed with grain after harvest.

Manage Tough-to-control and Resistant Kochia

The most effective management strategies for kochia in corn, soybeans and other crops should focus on preventing seed production throughout the year. Kochia is most susceptible to herbicide application prior to emergence and before weeds exceed 2 inches in height.

Consider pre- and post-harvest spraying where dense populations of kochia exist in your field. A pre-harvest application can speed drydown of weeds, improve harvest efficiency and alleviate residue problems that threaten to complicate fall tillage. At post-harvest, control kochia with appropriate herbicides or with tillage two weeks after harvest. Fall tillage reduces kochia seeds in the soil and will result in less residue and valuable soil moisture retained over the winter versus a fall herbicide application.

Do not plant into existing stands of kochia. Start weed-free at planting by using a burndown that is tankmixed with a pre-emergence residual herbicide just prior to or at planting.

Overwintering plants should be controlled early in the spring to ensure effective burndown. Growers may want to apply burndown herbicides with some of the residual herbicide in early spring and then apply the remainder of the residual herbicide at planting. To manage weed resistance, remember to practice herbicide diversity by choosing products with different modes of action from different classes of chemistry.

Crop competitiveness and crop rotation are two important cultural practices in cereals, corn and soybeans. Managing crop residue, controlling weeds and planting high-quality, uninfested seed all help establish a vigorous crop that can compete more effectively with emerging weeds for water, light, space and nutrients. Another helpful practice is rotation of grain crops such as corn, grain sorghum, proso millet, soybeans and sunflowers, depending upon geography.

Known Resistance in Kochia

Kochia has been resistant to ALS-inhibiting herbicides (Group 2) for more than two decades, and there is documented kochia resistance to glyphosate (Group 9), dicamba (Group 4) and triazines (Group 5). Research reported by the Weed Science Society of America (WSSA) indicates 2,4-D may no longer provide reliable kochia control. Dicamba-resistant kochia was confirmed in 2009 in Western Nebraska.

Bayer Solutions

Bayer has a broad portfolio to combat tough-to-control and resistant weeds. A well-thought-out herbicide program, using multiple modes of action, should be implemented to sustainably manage weeds. Before applying any herbicide, please read the entire label for the best possible results and to confirm the product is effective on the weeds you wish to control. Not every product is suitable for every situation, and use of the correct application technique will ensure the best results.

Please visit our corn and soybean pages for information on a portfolio of products from Bayer to help you better manage weeds.

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